percentage, low molecular weight vs. high molecular weight homologues, Alkane Proxy and Terrestrial Marine Discriminants). In general, these indexes indicated that the origin of aliphatic hydrocarbons affecting sediments and waters of Wadi El Bey were linked to both biogenic and petrogenic inputs, attesting the impact of plankton and terrestrial plants and of oil contamination, respectively. The average carbon chain length computation (ACL), used to further index the chemical environment, ranged from 25.5 to 31.1 in sediments and 47.9 - 116 in waters. This finding could depend on the severe disturbances suffered by the ecosystem as a consequence of heavy anthropogenic inputs. Petroleum contamination associated with high eutrophication rates in Wadi El Bey must be strictly controlled, due to possible harmful effects induced on ecosystem and humans.

Ge, T., Xue, Y., Jiang, X., Zou, L., Wang, X., 2020. Sources and radiocarbon ages of organic carbon in different grain size fractions of Yellow River-transported particles and coastal sediments. Chemical Geology 534, 119452.

http://www.sciencedirect.com/science/article/pii/S0009254119305819 14 13 The elemental (TOC, TN and C/N) and carbon isotope (Δ C and δ C) compositions of organic matter were measured in different grain size fractions of particles transported by the Yellow River and surface sediments in the Bohai Sea and the Yellow Sea. In the riverine particle and sediment samples, high OC contents were 13 14 a ssociated with small grain size fractions consisting mainly of clay minerals. The δ C and Δ C values of the bulk riverine particulate organic carbon (POC) collected from the Lijin and Xiaolangdi sites were relatively constant but varied significantly (-21.9‰ to -26.0‰ and -325‰ to -620‰, respectively) among the different 13 14 size fractions. In comparison, large spatial variations in δ C (-20.6‰ to -24.5‰) and Δ C (-188‰ to 14 -646‰) values, which increased seaward due to the difference in source carbon, were found for bulk TOC Δ C preserved in the surface sediments, but no significant differences were observed among the values in the different size fractions in most sediments. The different carbon isotopic values of the riverine POC and sedimentary TOC reflect differences in the sources, degradation and cycling time scales of the OC. The Yellow River exports very old (5220 ± 295 yrs) POC that is much older than the TOC (2457 ± 676 yrs) preserved in the surface sediments in the Bohai and Yellow seas. Calculations using a dual-isotope three end-member model indicate that pre-aged soil OC and ancient fossil OC represent major proportions (57 ± 16% and 30 ± 8%, respectively) of the riverine POC and that terrestrial biomass OC represents a minor proportion (13 ± 11%). The drainage environment of the river plays important roles in controlling the sources and ages of the riverine POC. In contrast, the TOC in the grain size fractions of the surface sediments in the Bohai and Yellow seas is dominated by marine-derived modern OC (47 ± 13%), followed by pre-aged soil OC (29 ± 9%) and ancient fossil OC (25 ± 14%). The ages of the TOC are determined mainly by the source input, rapid sedimentation, sediment minerology and decomposition of OC during early diagenesis in these large river-influenced marginal seas.

Ge, X., Shen, C., Selby, D., Feely, M., Zhu, G., 2020. Petroleum evolution within the Tarim Basin, northwestern China: Insights from organic geochemistry, fluid inclusions, and rhenium - osmium geochronology of the Halahatang oil field. American Association of Petroleum Geologists Bulletin 104, 329-355.

http://archives.datapages.com/data/bulletns/2020/02feb/BLTN17253/bltn17253.html The newly discovered Halahatang oil field in the northern Tarim Basin has a potential resource of more than 70 billion bbl of oil. Oil organic geochemical data from the Halahatang oil field indicate that the oils are of moderate maturity, biodegraded, and represent one oil family, derived from the same Paleozoic marine source. Modeling of coeval aqueous and hydrocarbon-bearing inclusion data provide fluid trapping temperatures and ∼ pressures of 100°C to 110°C and approximately 39 to 59 MPa ( 5656 - 8557 psi), respectively. The fluid inclusion data coupled with the previous basin model studies suggest a single prolonged oil migration event during the Permian. The Re - Os isotope data of the oil yields an early Permian Re - Os age of 285 ± 48 Ma. The age agrees with the timing of maturation of the Paleozoic source via burial history modeling but is slightly older ∼ ( 5 - 55 m.y.) than the oil migration and accumulation timing implied by the basin modeling coupled with fluid inclusion analysis and the published reservoir illite K - Ar dates. Thus, the oil Re - Os date suggests that oil generation in the Halahatang depression of the Tarim Basin occurred during the early Permian rather than the Silurian as previously proposed, with subsequent oil migration and accumulation occurring during the middle -